Autism Risk Gene May Generate a Tangle of Wiring the Brain

By Andrew Moseman | November 4, 2010 6:19 pm

BrainBlackAutism researchers already knew that a variant of gene called CNTNAP2 that appears in about one-third of people is associated with higher risk for developing the condition. A study this week out in Science Translational Medicine puts that genetic marker together with what it appears to do in the brain: cause too many connections inside the frontal lobe of the brain, but too few from there to other brain regions. That could be a key clue in unraveling the learning and language difficulties that frequently appear in autism spectrum disorders.

The gene produces a protein called CASPR1 and is active during brain development — mostly during frontal-lobe development. “During early development, it is localized to parts of brain that are ‘more evolved’ — areas where learning and language happen, the frontal lobes where really complex thinking takes place,” says Ashlee Scott-van Zeeland, a postdoctoral fellow at the Scripps Translational Science Institute in La Jolla, Calif., and lead author of the study. “[It is] thought to help structure the brain.” [TIME]

To study its effects, Scott-Van Zeeland and company studied 32 kids between 11 and 13 in age. Some were autistic, some not, and many of the non-autistic kids carried the CNTNAP2 gene variant. The scientists examined the children’s brains through fMRI while the kids played a game intended to stimulate brain regions that the gene affects.

Regardless of whether the kids had autism or not, children with the CNTNAP2 “risk” gene showed more activity in the frontal lobe of the brain (specifically, inside the prefrontal cortex) during a “language learning” task than those without the risk gene. In those without the risk gene, activity in the prefrontal cortex decreased during the task. Instead, there was more connectivity between the frontal lobe and other areas of the brain, including the left side of the brain, which is involved with language. [BusinessWeek]

Curious to learn more, the team studied a further 40 kids who did not have autism to see what happened with the gene, Reuters reports. The same pattern emerged: Kids with the risk variant of the gene, though they didn’t have autism, did show the extra connections in the front frontal lobe.

Scott-Van Zeeland said researchers know that autism is caused by more than one gene, but the CNTNAP2 gene helps explain part of the picture. “One third of the population carries this variant in its DNA,” [coauthor Daniel] Geschwind cautioned. “It’s important to remember that the gene variant alone doesn’t cause autism — it just increases risk.”[Reuters]

But while CNTNAP2 is only part of the picture, the team’s findings seem to agree with what’s already known about autism.

The new findings lend support to the “intense world” theory of autism, which has posited that patterns of brain circuitry that result in excessive functioning in some regions may lead to extremes in attention and perception, which can produce both the deficits — and the sometimes extraordinary intellectual talents — that characterize some people with autism. [TIME]

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Image: iStockphoto

CATEGORIZED UNDER: Mind & Brain
  • http://billieroseb@hotmail.com Billie

    Wow very facinating thankyou keep up the great work

  • JOHN ROLIN

    This new discovery will not make any difference to the trial lawyers. They will continue to file lawsuits claiming that immunization injections cause Autism. Do I hear John Edwards calling?

  • Anthony

    @John Rolin

    John you are thinking inside the box. Think outside. This gene has identified as a ‘Risk’ gene. It’s very possible that anyone with the ‘Risk’ gene that has a certain class of vaccination will develop autism. If that can be determined they it’s possible they can develop a variant of vaccination that is safe f0r those WITH the ‘Risk’ gene.

  • Mary McK

    Well, isn’t it appropriate that when you pronounce the Gene, it is CAN’T NAP!

  • Michael

    Try this on 100 more kids, and maybe a clearer pattern will emerge.

    What did the MRI reveal when the children with the gene were given a math problem?

  • Mark

    @Anthony:
    Anthony, you are thinking without a box at all.

    What you suggest vis a vis “a risk” gene with a particular environmental exposure such as a vaccine would be possible, if it were not for the fact that there is a tremendous amount of evidnce that vaccines are not related to autism in any way. Since 1/3rd of the population carries the CTNAP2 polymorphism, prior work would have revealed such a link.

    There is no need to develop a vaccination that is safe for people with this polymorphism, since we already know that existing vaccines are safe for them.

  • RAJ

    CTNAP2 variations have been located in a region of chromosome 7. It is also associated with many developmental problems including autism, schizophrenia, mental retardation and childhhood language disorders as well as the vast majority of people who are not affected in any way.

    This is a tiny risk factor that is not diagnosis specific as are all the common genetic variations and copy number variations.

    If there is any tiny risk factor it is not with autism but rather risk for neurodevelopmental alterations common in the developmental disorders.

    Infact, no genetic variation has ever been identified that is a diagnosis specific susceptability gene.

  • http://www.collegeplanningabc.com College

    I’d be inclined to acknowledge with you here. Which is not something I typically do! I enjoy reading a post that will make people think. Also, thanks for allowing me to comment!e if it’s the right choice for you.

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